A NOVEL HBT DISTRIBUTED-AMPLIFIER DESIGN TOPOLOGY BASED ON ATTENUATION COMPENSATION TECHNIQUES

We report on a novel HBT distributed amplifier design which achieves t he highest gain-bandwidth product (GBP) per device f(T) so far reporte d for HBT distributed amplifiers, This paper introduces a new design t opology for HBT DA's which incorporates attenuation compensation on bo th the input and output transmission lines, A four-section HBT DA usin g this novel topology achieves a gain of 15 dB and a 3-dB bandwidth of > 15 GHz. The resulting gain-bandwidth product is 84 GHz. When normal ized to the device f(T), this DA achieves the highest normalized gain- bandwidth-product figure of merit for HBT DA's, approximate to 3.67, w hich is a 55% improvement over existing state-of-the-art performance. Attenuation compensation of the input transmission line is realized us ing HBT active impedance transformations. The resulting transistor con figuration consists of a common-collector driving a common-emitter-cas code transistor pair. This configuration offers 15-20 dB more availabl e gain for the device unit cell, and results in gain-bandwidth product improvements of 200% over a conventional common-emitter DA configurat ion. This paper will discuss the design theory, techniques, and measur ements of this newly developed HBT distributed amplifier topology.